KR20210068530A - Organic electroluminescent material, manufacturing method thereof, and organic electroluminescent device - Google Patents

Abstract

The present invention provides an organic electroluminescent material, a manufacturing method thereof, and an organic electroluminescent device including the organic electroluminescent material, for example, an organic light emitting diode (OLED). The organic electroluminescent material is a compound based on imidazole [1,5-a] [1,8] naphthyridine, and has the structure of the following formula I . The compound has high stability, and the prepared organic electroluminescent device has high efficiency.

Description

Organic electroluminescent material, manufacturing method thereof, and organic electroluminescent device

The present invention relates to the field of organic electroluminescent materials, and more particularly, imidazole [1,5-a] [1,8] naphthyridine (imidazole [1,5-a] [1,8] naphthyridine) based A compound is provided, and a light emitting device is further provided.

OLED is an organic light-emitting diode (Organic Light-Emitting Diode) or an organic light-emitting device (Organic Light-Emitting). OLED is a self-luminous device that does not require a backlight and has characteristics such as fast response speed, low driving voltage, high luminous efficiency, high resolution, and wide viewing angle, making it a next-generation display and lighting technology. In particular, application prospects are high in mobile phones, computers, TVs, and curved and foldable electronic products.

Currently, two types of light-emitting materials are applied to OLEDs: fluorescent materials and phosphorescent materials. The light emitting material adopted for the initial device was mainly organic small molecule fluorescent material, but according to spin statistics quantum science, the theoretical internal quantum efficiency of the fluorescent material is only 25%. In 1998, Professor Forrest of Princeton University and Professor Thompson of the University of Southern California discovered the phenomenon of phosphorescence electroluminescence of metal-organic compound molecular materials at room temperature. By using the strong self-rotating orbital bonding of heavy metal atoms, it effectively promotes the intersystem crossing (ISC) of electrons from singlet to triplet, so that the singlet and triplet elicitor generated by the electrical excitation of the OLED device is sufficiently reduced. It is possible to achieve the theoretical internal quantum efficiency of light-emitting materials up to 100%.

In OLED materials, since the rate of hole transport in most organic electroluminescent materials is one or two orders of magnitude larger than the rate of electron transport, an imbalance in the number of electrons and holes in the light emitting layer is likely to occur, so the obtained device efficiency is also relatively low. Therefore, the selection and optimization of the host material in the light emitting layer has a great influence on improving the efficiency and lifespan of the organic electroluminescent device. CBP has been widely applied as a light emitting layer of a phosphorescent device since its invention. Although the carbazole group among them makes CBP have a relatively high triplet energy level, it can be used in the light emitting layer of phosphorescent materials, but since it is mainly a hole transport type material, the rate of electron transport is relatively low, resulting in an imbalance in carrier injection and transport. fairly easy to do In addition, the glass transition temperature Tg of CBP is relatively low, which is not advantageous for stable use of the device. Therefore, the development of a light emitting layer host material with high stability and balanced carrier transport is of great value for the widespread use of organic electroluminescent devices.

The present invention provides an imidazole[1,5-a][1,8]naphthyridine-based compound having relatively good thermal stability and high hole/electron transport balancing ability. The present invention further provides the application of the above material in an organic light emitting diode (OLED), and a device manufactured by adopting the organic electroluminescent compound has advantages of high electroluminescence efficiency, excellent color purity, and long lifespan.

The organic electroluminescent material is a compound having the following structural formula (I).

wherein Ar is C6-C30 substituted or unsubstituted aryl, C5-C30 substituted or unsubstituted aryl containing one or more heteroatoms, N-aryl substituted carbazolyl, N-aryl substituted indenocarbazole (indenocarbazole) derivative substituents, diarylamine, R ₁ -R ₈ substituted diarylamine and its cyclic derivative Cy. Z is C(R ₉ ) ₂ , Si(R ₉ ) ₂ , O, S,NR ₉ , SO ₂ . wherein R ₁ -R ₉ are independently hydrogen, deuterium, halogen, unsubstituted alkyl, halogenated alkyl, deuterated alkyl, cycloalkyl, unsubstituted aryl, alkyl substituted aryl, alkoxy, cyano, carbazolyl, or diphenylamine, or R ₁ -R ₉ independently form a 5-8 membered ring with adjacent groups

;

;

L is selected from phenylene, biphenylene, and naphthylene.

R is selected from hydrogen, deuterium, substituted or unsubstituted C6-C10 aryl, C6-C10 heteroaryl.

Ar is phenyl, naphthyl, biphenyl, phenanthryl, fluorenyl, arylfluorenyl, pyrenyl, dibenzofuranyl, dibenzothienyl, benz Imidazolyl, pyridyl, pyrimidinyl, quinolinyl, isoquinolinyl, triazinyl, pyrrolyl, furyl ), thiazolyl, quinazolinyl, triazolyl, benzothiazolyl, benzothiadiazolyl, 1,2,4-triazolyl (1,2,4) -triazolyl), triphenylamine, arylcarbazolyl, N-aryl substituted carbazolyl, diphenylamine, azetidinyl, azetidine (acridine) derivative substituent, phenoxazinyl (phenoxazinyl) and its derivative substituents, phenothiazinyl and its derivative substituents. R is selected from hydrogen, phenyl, naphthyl, pyridyl.

Ar is preferably phenyl, naphthyl, biphenyl, phenanthryl, fluorenyl, arylfluorenyl, pyrenyl, dibenzofuranyl, dibenzothienyl, benzimidazolyl, pyrimidinyl, triazinyl, quina zolinyl, 1,2,4-triazolyl, N-phenyl-carbazolyl, diphenylamine, azetidinyl and azetidine derivative substituents.

Certain specific, non-limiting examples with compounds of structure I are as follows.

The method for producing the organic electroluminescent material includes the following steps.

(1) Compound A is provided.

(2) under alkaline conditions, using tetrakis(triphenylphosphine)palladium as a catalyst, and using a boric acid compound containing Ar or pinacol borate containing Ar and to give the compound of formula (I).

.A:

.

The preparation method of the compound A is as follows.

A) Compound B is obtained by formate reaction of 2-bromo-1,8-dinaphthyridine with R under the action of n-butyllithium.

B) Compound A is obtained by reaction of compound B with a formaldehyde compound CHO-L-Br of bromide L.

The formate of R is methyl formate of R.

The imidazole [1,5-a] [1,8] naphthyridine compound of the present invention can be applied to an organic electroluminescent device, a solar cell, an organic thin film transistor, or an organic sensor field.

The present invention further provides an organic electroluminescent device. The device includes an anode, a cathode and an organic layer. The organic layer includes at least one of a light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer. At least one of the organic layers comprises an imidazole[1,5-a][1,8]naphthyridine compound according to formula (I).

Here, the definitions of Ar, L, and P are the same as described above.

Here, the organic layer is a light emitting layer and an electron transport layer.

Alternatively, the organic layer is a light emitting layer, a hole injection layer, a hole transport layer and an electron transport layer.

Alternatively, the organic layer is a light emitting layer, a hole injection layer, a hole transport layer, an electron transport layer and an electron injection layer.

Alternatively, the organic layer is a light emitting layer, a hole transport layer, an electron transport layer, or an electron injection layer.

Alternatively, the organic layer is a light emitting layer, a hole transport layer, or an electron injection layer.

Preferably, the layer in which the imidazole[1,5-a][1,8]naphthyridine-based compound according to the structural formula (I) is located here is a light-emitting layer.

Preferably wherein the imidazole[1,5-a][1,8]naphthyridine containing compound according to formula I is a compound of formula 1-36.

When the imidazole [1,5-a] [1,8] naphthyridine-containing compound according to Structural Formula I is used for manufacturing a light emitting device, it can be used alone or mixed with other compounds, and two or more of Structural Formula I The compounds may be used simultaneously.

A more preferred method of the organic electroluminescent device of the present invention is as follows. That is, the organic electroluminescent device includes an anode, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer and a cathode, wherein the light emitting layer comprises a compound of formula I, and more preferably, the compound contained in the light emitting layer has a structure It is a compound of 1-36.

The total thickness of the organic electroluminescent device organic layer of the present invention is 1 to 1000 nm, preferably 50 to 500 nm.

The organic electroluminescent device of the present invention can obtain blue light, green light, yellow light, red light or white light by using other materials in combination when the compound having the structural formula I of the present invention is used.

In the organic electroluminescent device of the present invention, each layer of the organic layer may be prepared through a vacuum deposition method, a molecular beam deposition method, a dipping method dissolved in a solvent, a bar coating method, or inkjet printing. The metal motor can be manufactured using a vapor deposition method or a sputtering method.

According to device experiments, the imidazole[1,5-a][1,8]naphthyridine-containing compound according to Structural Formula I of the present invention has relatively good thermal stability and high hole/electron transport balancing ability. The device manufactured by the organic electroluminescent compound has advantages of high electroluminescence efficiency, excellent color purity, and long lifespan.

1 is a DSC spectrum of compound 29.
2 is a structural diagram of an organic electroluminescent device.

Hereinafter, an embodiment for implementing the implementation method of the present invention will be described. These examples should not be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted.

synthesis of intermediates

Synthesis of Intermediate 1

2-bromo-1,8-dynaphthyridine (10 g, 47.84 mmol) and anhydrous THF (100 ml) were added to a three-necked flask, stirred at -50 ° C under nitrogen protection for 20 minutes, and then n using a static pressure droplet funnel -Butyllithium in n-hexane solution (2.2M, 26ml, 57mmol) is added dropwise. After completion of the dropwise addition, the temperature was continuously maintained and the mixture was stirred for 30 minutes. Then, a THF solution of methyl benzoate (6.84 g, 50.2 mmol) was added dropwise, and then the temperature was slowly raised to room temperature and stirred overnight. After the reaction is completed, quenching is performed with a saturated ammonium chloride solution and the organic phase is separated. The inorganic phase is extracted with ethyl acetate and the organic phase is combined. The product was purified by column chromatography to obtain 7.7 g, and the yield was 71%.

Synthesis of Intermediate 2

The raw material for synthesis is methyl 4-picolinate, the synthesis method is consistent with the intermediate 1, and the yield is 68%.

Synthesis of Intermediate 3

In a flask, add Intermediate 1 (3 g, 12.8 mmol), p-bromobenzaldehyde (2.37 g, 12.8 mmol), ammonium acetate (29.6 g, 0.38 mol), and acetic acid 60 mL. It is heated to 130° C. under a nitrogen atmosphere, and the reaction is 15 hours. After completion of the reaction, the acetate was removed under reduced pressure under cooling, water was added, and the organic phase was extracted with dichloromethane, collected, dried and concentrated to obtain a crude product. The crude product was purified by silica gel column chromatography to obtain 3.5 g, and the yield was 70%.

Synthesis of Intermediate 4

The raw material for synthesis is m-bromobenzaldehyde, and the synthesis method is consistent with Intermediate 3, and the yield is 65%.

Synthesis of Intermediate 5

In a flask, add Intermediate 2 (6 g, 25.5 mmol), m-bromobenzaldehyde (4.7 g, 25.5 mmol), ammonium acetate (49 g, 0.64 mol), and 100 mL of acetic acid. It is heated to 130° C. under a nitrogen atmosphere, and the reaction is 16 hours. After completion of the reaction, the acetate was removed under reduced pressure under cooling, water was added, and the organic phase was extracted with dichloromethane, collected, dried and concentrated to obtain a crude product. The crude product was purified by silica gel column chromatography to obtain 6 g, and the yield was 59%.

Example 1 - Synthesis of compound 18

Intermediate 4 (1 g, 2.5 mmol), 2,4-diphenyl-6-((3-pinacol borate) phenyl)-1,3,5-triazine (1.2 g, 2.75 mmol), tetra in a round bottom flask Add tetrakis(triphenylphosphine)palladium (0.29 g, 0.25 mmol), potassium carbonate (0.86 g, 6.2 mmol) and dioxane/water (10 ml/2 ml). The reaction mixture was heated to 110° C. under a nitrogen gas atmosphere and stirred for 10 hours. After completion of the reaction, washed with water, extracted with dichloromethane, and concentrated to obtain a crude product, purified by silica gel column chromatography to give 1.27 g, the yield is 81%. Ms(ESI): 629.2 (M+1).

Example 2 - Synthesis of compound 21

Intermediate 3 (1 g, 2.5 mmol), N-phenyl-3-carbazoleboronic acid (0.79 g, 2.75 mmol), tetrakis (triphenylphosphine) palladium (0.29 g, 0.25 mmol), potassium carbonate in a round bottom flask (0.86 g , 6.2 mmol) and toluene/water (10 ml/2 ml) are added. The reaction mixture was heated to 110° C. under a nitrogen gas atmosphere and stirred for 8 hours. After completion of the reaction, washed with water, extracted with dichloromethane, and concentrated to obtain a crude product, purified by silica gel column chromatography to obtain 1.04 g, the yield is 74%. Ms(ESI): 563.2 (M+1).

Example 3 - Synthesis of compound 29

물을 첨가하여 세척하고 디클로로메탄으로 추출하며, 농축하여 조생성물을 수득하고, 실리카겔 칼럼 크로마토그래피로 정제하여 3.08g을 수득하였으며, 수율은 85%이다. Ms(ESI): 728.3 (M+1). 유리 전이 온도는 99℃이며, 도 1은 화합물 29의 DSC 스펙트럼이다.Intermediate 5 (2g, 5mmol), 3-(10H-spiro[acridine-9,9'-fluoren]-10-yl)phenyl)boronic acid (3-(10H-spiro[acridine- 9,9'-fluorene]-10-yl)phenyl)boronic acid) (2.47g, 6mmol), tetrakis(triphenylphosphine)palladium (0.58g, 0.5mmol), potassium carbonate (1.7g, 12.5mmol) , dioxane/water (20ml/4ml) is added. The reaction mixture was heated to 110° C. under a nitrogen gas atmosphere and stirred for 10 hours. After completion of the reaction,

The product was washed by adding water, extracted with dichloromethane, and concentrated to give a crude product, which was purified by silica gel column chromatography to obtain 3.08 g, the yield was 85%. Ms(ESI): 728.3 (M+1). The glass transition temperature is 99°C, and FIG. 1 is a DSC spectrum of compound 29.

Example 4-6

Fabrication of organic electroluminescent devices

An OLED is manufactured using the compound according to an embodiment of the present invention.

First, the transparent conductive ITO glass substrate 110 (the anode 120 is on the upper surface) is washed with deionized water, ethanol, acetone, and deionized water in order, and then treated with oxygen plasma for 30 seconds.

Then, a hole injection layer 130 (HATCN) having a thickness of 5 nm is deposited.

Then, a 50 nm-thick hole transport layer 140 (TAPC) is deposited on the hole injection layer.

Next, 10 wt% Pt-1 doped with an embodiment compound having a thickness of 10 nm is deposited on the hole transport layer as the light emitting layer 150 .

Then, an electron transport layer 160 (TmPyPb) having a thickness of 50 nm is deposited on the emission layer.

Finally, LiF having a thickness of 1.2 nm is deposited as the electron injection layer 160 , and Al having a thickness of 100 nm is deposited as the device cathode 180 .

The manufactured device (the structure is as shown in FIG. 2) was ^{measured for efficiency when the current density was 1000 cd/m 2} using a Photo Reasearch PR650 spectrometer, which is shown in Table 1.

Comparative Example 1

The light emitting layer was the same as in Example 4 except that CBP was used instead of the compound of the present invention.

The manufactured device (the structure is as shown in FIG. 2) was ^{measured for efficiency when the current density was 1000 cd/m 2} using a Photo Reasearch PR650 spectrometer, which is shown in Table 1.

Table 1

As can be seen from Table 1, the efficiency of the organic electroluminescent device prepared with the imidazole [1,5-a] [1,8] naphthyridine-based compound of the present invention under the same conditions is higher than that of Comparative Example. As described above, the compound of the present invention has high stability and the organic electroluminescent device prepared in the present invention has high efficiency.

Among the elements, the structural formula is as follows.

Therefore, using the imidazole[1,5-a][1,8]naphthyridine-based compound of the present invention as a host, higher efficiency can be obtained than a device manufactured with CBP. Under the same test conditions, when the device manufactured by CBP was 1000 cd/m ² , the current efficiency was 41.9 cd/A, the power efficiency was 29.1 lm/W, and the external quantum efficiency was 12.1%. However, all devices manufactured by the compound of the present invention were able to obtain an effect higher than the above-mentioned efficiency. In addition, the glass transition temperature T _g of CBP is 62 ° C., but the compound of Example 29 of the present invention has a higher glass transition temperature T _g (99 ° C), the glass transition temperature is higher, and the device light emitting layer morphological stability is excellent. It is brighter and more in line with the requirements for the host material of organic light emitting diodes.

110: glass substrate
120: positive electrode
130: hole injection layer
140: hole transport layer
150: light emitting layer
160: electron transport layer
170: electron injection layer
180: cathode

Claims (13)

In the organic electroluminescent material,
It is a compound having the formula (I),

wherein Ar is C6-C30 substituted or unsubstituted aryl, C5-C30 substituted or unsubstituted aryl containing one or more heteroatoms, N-aryl substituted carbazolyl, N-aryl substituted indenocarbazole (indenocarbazole) derivative substituents, diarylamine, R ₁ -R ₈ substituted diarylamine and its cyclic derivatives Cy, Z is C(R ₉ ) ₂ , Si(R ₉ ) ₂ , O , S,NR ₉ , SO ₂ , wherein R ₁ -R ₉ are independently hydrogen, deuterium, halogen, unsubstituted alkyl, halogenated alkyl, deuterated alkyl, cycloalkyl, unsubstituted aryl, alkyl substituted aryl , alkoxy, cyano, carbazolyl, diphenylamine (diphenylamine), or R ₁ -R ₉ independently form a 5-8 membered ring with an adjacent group,

;
L is selected from phenylene, biphenylene, and naphthylene;
R is selected from hydrogen, deuterium, substituted or unsubstituted C6-C10 aryl, and C6-C10 heteroaryl. According to claim 1,
Ar is phenyl, naphthyl, biphenyl, phenanthryl, fluorenyl, arylfluorenyl, pyrenyl, dibenzofuranyl, dibenzothienyl, benz Imidazolyl, pyridyl, pyrimidinyl, quinolinyl, isoquinolinyl, triazinyl, pyrrolyl, furyl ), thiazolyl, quinazolinyl, triazolyl, benzothiazolyl, benzothiadiazolyl, 1,2,4-triazolyl (1,2,4) -triazolyl), triphenylamine, arylcarbazolyl, N-aryl substituted carbazolyl, diphenylamine, azetidinyl, azetidine (acridine) derivative substituent, phenoxazinyl (phenoxazinyl) and its derivative substituents, phenothiazinyl and its derivative substituents; R is selected from hydrogen, phenyl, naphthyl, and pyridyl. 3. The method of claim 2,
Ar is phenyl, naphthyl, biphenyl, phenanthryl, fluorenyl, arylfluorenyl, pyrenyl, dibenzofuranyl, dibenzothienyl, benzimidazolyl, pyrimidinyl, triazinyl, quinazolinyl, An organic electroluminescent material selected from 1,2,4-triazolyl, N-phenyl-carbazolyl, diphenylamine, azetidinyl and azetidine derivative substituents. 3. The method of claim 2,
An organic electroluminescent material, characterized in that it is a compound having the following structural formula.

5. The method of claim 4,
An organic electroluminescent material, characterized in that it is a compound having the following structural formula.

(1) providing compound A;
(2) under alkaline conditions, using tetrakis(triphenylphosphine)palladium as a catalyst, and using a boric acid compound containing Ar or pinacol borate containing Ar to obtain a compound of formula (I);

A method for producing an organic electroluminescent material according to any one of claims 1 to 5, comprising a. 7. The method of claim 6,
The preparation method of the compound A is as follows,
A) under the action of n-butyllithium, 2-bromo-1,8-dinaphthyridine and R formate reaction to obtain compound B;
B) A process for producing compound A, characterized in that compound B and L bromide are reacted with formaldehyde compound CHO-L-Br to obtain compound A. 8. The method of claim 7,
The formate salt of R is a production method, characterized in that the methyl formate of R (methyl formate). Application of the organic electroluminescent material according to any one of claims 1 to 5 in organic electroluminescent devices. In the organic electroluminescent device,
The device includes an anode, a cathode and an organic layer, the organic layer includes at least one of a light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, wherein at least one of the organic layers is An organic electroluminescent device comprising the organic electroluminescent material according to claim 1 . 11. The method of claim 10,
The organic layer includes a light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, and the organic electroluminescent material according to any one of claims 1 to 5 is an organic electroluminescent layer, characterized in that the light emitting layer light emitting element. 12. The method of claim 11,
An organic electroluminescent device, characterized in that the organic electroluminescent material according to any one of claims 1 to 5 is used alone in the light emitting layer or mixed with other compounds. 11. The method of claim 10,
The total thickness of the organic layer is 1 to 1000 nm, vacuum deposition method, molecular beam deposition method, dipping method dissolved in a solvent, an organic electroluminescent device, characterized in that obtained by manufacturing a bar coating method or inkjet printing method.

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